Fuel compositions



tates This invention relates to gasoline compositions containing novel anti-knock additives.

In accordance with the present invention, compounds having the formula C,,O where n is an odd number, for example, carbon suboxide (C and pentacarbon dioxide (C O are used as gasoline anti-knock additives. Also, graphitic oxide, which is formed by contacting graphite with a strong oxidizing agent, and carbon black containing a high content of chemisorbed oxygen are employed as gasoline anti-knock additives in accordance with this invention.

Carbon monoxide, when introduced into spark ignition engine combustion chambers in amount in excess of that normally produced during combustion of gasoline hydrocarbons, reduces engine knocking. The fuel additives of this invention are believed to produce their anti-knock efiect due to the fact that at conditions in spark engine combustion chambers during engine operation the additives decompose with the evolution of copious quantities of carbon monoxide.

In carrying out the invention, the anti-knock additives are incorporated in gasoline hydrocarbons in amount sufiicient to improve the anti-knock characteristics of the fuel. Normally amounts of the additives in the range of about 0.1% to 5% by weight of the fuel and preferably about 0.5% to 2% of the fuel give good results. However, amounts outside this range can on occasion be used.

The gasoline to which the anti-knock compounds are added comprises mixtures of hydrocarbons boiling in the range of about 80 F. to 440 F. and usually about 90 F. to 400 F. The gasoline compositions can contain, in addition to the additives of this invention, any of the gasoline additives commonly used in the art. Organometallic anti-knock additives such as tetraethyl lead, iron carbonyl, bis-cyclopentadienyl iron and the like can be included in the compositions of this invention. These organo-metallic additives are commonly used in amounts in the range of about 0.5 to 20 g. per gallon of fuel. Other gasoline additives such as scavengers, anti-icing agents, detergents, and the like can be used.

Compounds having the general formula C,,O; where n is an odd number greater than i are suitable gasoline antiknock additives in accordance with this invention. Carhon suboxide, C 0 is an example of this class of compounds. Carbon suboxide is made in accordance with procedures which are known in the art. One such procedure comprises heating malonic acid with phosphorus pentoxide to produce carbon suboxide. C 0 pentacarbon dioxide, is another specific example of compounds of this class which cna be used. Pentacarbon dioxide is made, for example, through decomposition of carbon suboxide. Other compounds having the formula C,,O where n is an odd number greater than 1 can be used. These compounds are generally sutficiently soluble in gasoline hydrocarbons as not to require use of mutual solvents or dispersing agents although such solvents and dispersing agents can be used if desired.

Graphrtic oxide which 15 used as a gasoline anti-knock additive in accordance with this invention is formed by subjecting graphite to the action of strong oxidizing agents in accordance with procedures known in the art. The product of the graphite oxidation is known in the art atet 2 as graphitic oxide or graphitic acid. The term graphitic oxide in the present specification includes both those compounds identified as graphitic oxide and graphitic acid in the art. The composition of the product of graphite oxidation varies somewhat depending upon the oxidizing conditions. Compounds having the formula CHI-1405, 011E406, and the like, have been formed. Any of the strong oxidizing agents, e.g. hot nitric acid and potassium chlorate, known in the art for oxidizing graphite can be used in preparing graphitic oxide for use in this invention.

Carbon black containing chemisorbed oxygen can be used as a gasoline anti-knock additive in accordance with the present invention. It is preferred that the carbon black contain a high content of chemisorbed oxygen, e.g. greater than 5% by weight and preferably greater than 10% by weight. Certain carbon blacks, e.g. highcolor chnanel blacks (HCC-l), as normally manufactured have high chemisorbed oxygen contents and can be used directly as a gasoline additive in accordance with this invention. Other blacks should first be treated to increase the content of chemicorbed oxygen prior to use in this invention. Such treatment comprises contacting the blacks with oxygen or oxygen-containing gases at mildly elevated temperatures, e.g. F. to 250 F.

The graphitic oxide and carbon black used as antiknock additives in the invention are normally solid compounds which are relatively insoluble in gasoline hydrocarbons. It is preferred to incorporate these additives in gasoline by reducing the particle size of the anti-knock additives such that when admixed with gasoline hydrocarbons the additives remain in colloidal dispersion therein. If desired, dispersing agents can be used to insure uniform dispersion of the anti-knock compounds in the fuel compositions. Other means known in the art for uniformly incorporating solid particles in liquid hydrocarbons can be used.

The following illustrates practice of the invention:

Carbon suboxide, graphitic oxide having the formula C H O and carbon black containing about 11% by weight chemisorbed oxygen are incorporated respectively in different samples of gasoline hydrocarbons such that the additives comprise 1% of the fuel compositions. These resulting compositions when used as fuel in spark ignition internal combustion engines have'improved antiknock characteristics.

1 claim:

1. Fuel composition consisting essentially of gasoline hydrocarbons and an anti-knock amount of a compound selected from the group consisting of carbon suboxide, pentacarbon dioxide, graphitic oxide, and carbon black containing more than 5% by weight of chemisorbed oxygen.

2. Composition according to claim 1 wherein said compound is carbon suboxide.

3. Composition according to claim 1 wherein said compound is pentacarbon dioxide.

4. Composition according to claim 1 wherein said compound is graphitic oxide.

5. Composition according to claim 1 wherein said compound is carbon black containing more than 5% by weight of chemisorbed oxygen.

References Cited in the file of this patent UNITED STATES PATENTS 2,698,008 Hughes Dec. 28, 1954 2,727,496 Thomas Dec. 20, 1955 FOREIGN PATENTS 246,132 Great Britain Aug. 11, 1927 313,889 Great Britain Sept. 18, 1930 539,285 Great Britain as..- Sept. 3, 1941 

1. FUEL COMPOSITION CONSISTING ESSENTIALLY OF GASOLINE HYDROCARBONS AND AN ANTI-KNOCK AMOUNT OF COMPOUND SELECTED FROM THE GROUP CONSISTING OF CARBON SUBOXIDE, PENTACARBON DIOXIDE, GRAPHIC OXIDE, AND CARBON BLACK CONTAINING MORE THAN 5% BY WEIGHT OF CHEMISORBED OXYGEN. 